The invention is directed to a process for the production of thiosemicarbazide by formation of hydrazine thiocyanate and converting this into the thiosemicarbazide.
It is known that hydrazine thiocyanate is formed if a salt of thiocyanic acid is brought together with hydrazine or a salt of hydrazine in aqueous medium and that the hydrazine thiocyanate is converted into thiosemicarbazide at a higher temperature. For example, ammonium thiocyanate is mixed with hydrazine, water, and an alkanol having 3 to 5 carbon atoms and this mixture heated to boiling after addition of catalytic amounts of acetone (Great Britain patent No. 1118133) or ammonium thiocyanate and hydrazine sulfate are dissolved in water, and this solution is heated to boiling after addition of catalytic amounts of acetaldehyde (German Pat. No. 1274574). A disadvantage of the known processes is that equivalent amounts of byproducts, for example, ammonia or ammonium sulfate, form, and these byproducts can either not be recovered and used or at all events they can only by recovered and used at considerable expense.